Why Do Crickets Chirp?

The cricket’s call, a sound familiar to almost everyone around the globe, can vary from isolated clicks to repetitive chirps to long trills. While the females are mute, most male crickets can be loud musicians, producing species-specific songs up to 100 decibels, about the same volume as a motorcycle or a power drill. They create their songs by a method that is very different from human vocalization.

Cricket Wings Are Acoustic Instruments

Male crickets use specialized parts of their tough and leathery front wings to create sound in much the same way that you might use a musical instrument. Each front wing has a hard ridge running across it, and on the underside of the ridge is a file, a single row of stiff notches similar to teeth on a comb. At the outer tip of the file is a small bump called a scraper.

Movements Produce Sound

To make their distinctive sound, the male crickets lift their wings and rub them together, running the scraper of one wing across the file of the other. This action, similar to running your thumbnail down the tips of a comb, is called stridulation. It creates vibrations that are then amplified by a flexible membrane right next to the file. This section of the wing is known as the harp due to its triangular shape, even though it acts more like a drum.

How Chirps Can Vary

Cricket songs can vary. If field crickets open and close their wings several times, it produces multiple chips. Longer, slower strums may produce the trills characteristic of tree crickets. When a mole cricket calls, he may stand at the entrance to his burrow in the ground. This position boosts his song’s volume, just as you can amplify a cell phone’s sound by placing it in an open cup or can. Crickets chirp faster in warm weather, and the snowy tree cricket has even earned a reputation as a thermometer since you can count the number of chirps for 14 seconds and then multiply by 40 to get a close approximation of the Fahrenheit temperature.

Why Does a Cricket Call?

Scientists say there are four main reasons why crickets make noise, each of which has its own different song.

He is trying to attract a mate. This song is one of the loudest and also the most common. It is a general call, directed at any female cricket within earshot. It is also a warning to other males to stay away from his territory.

He wants to woo a particular female cricket. If the male spots a female in the area, his song changes to a quieter love song, directed at her specifically.

He is celebrating his mating success. Often after mating, the male will announce it with a short song.

He is feeling aggressive or threatened. If another male approaches him, or if he sees another threat, he makes this sound.

Time and Season

Cricket songs increase at certain times of the day and seasons of the year. The reason for the time difference is that most crickets are nocturnal, less active during the day and more active at night. The seasonality, on the other hand, is due to the cricket life cycle. They only live one season and typically mate in late summer or early fall, which is when you hear them the most.

Resources

Fountain, Henry. “Block That Chirp: Volume Control in Crickets.” New York Times. N.p., 31 Jan. 2006. Web. 17 June 2016.